With turbo fan engines mounted on aircraft, it is generally known that larger bypass ratios lead to better fuel efficiency. Here, “bypass ratio” is defined as the ratio of the amount of air passing through portions other than the core engine to the amount of air passing through the core engine. However, there is a limit to the miniaturization of the size of the core engine. As such, in order to increase the bypass ratio, the diameter of the engine body must be enlarged to increase the amount of bypassed air.
However, as illustrated in FIG. 7, in the case of an aircraft 50 on which an engine 52 is mounted under a main wing 51, clearance from the ground must be secured. Therefore, there is also a limitation on the diameter of the main body of the engine 52. Accordingly, the upper limit of the bypass ratio of turbo fan engines is about 10.
Patent Document 1 below recites one turbo fan engine which generates thrust force and at least one electromagnetic driving fan which generates thrust force being placed on one wing, and that the electromagnetic driving fan is driven by power generated by a power generator provided in the turbo fan engine.